The present invention relates to improvement in or relating to numerical control equipment, and more particularly to numerical control equipment which enables a movable machine part to continuously move even in the case of executing in succession a plurality of blocks having a short execution time.
Conventional numerical control equipment is arranged so that, upon each readout of one block of command information, it converts data accommodated in the block into an execute form and then controls the operation of a movable machine part in accordance with the converted data. This conversion is to change the data held in the block into a form for easy processing in the numerical control equipment; for example, data given in the form of a decimal number is transcribed into a hexadecimal number.
However, according to an arrangement in which the above-mentioned processing is performed upon each readout of one block of command information and processing of the next block is not initiated until processing of the current block is completed, the movable machine part will be at a standstill until data in an execute form is produced. Such a stoppage of the movable machine part between adjacent blocks will not only impair the cutting efficiency but also pose the problems that the workpiece is stained with a cutter mark and subject to vibration.
To avoid this, the prior art numerical control equipment employs first and second buffers for storing data converted into an execute form. While processing corresponding to the preceding block (N-1) is being performed on the basis of data stored in one buffer (the first buffer, for example), data held in the current block (N) is converted into the execute form and then stored in the second buffer (the second buffer). Upon completion of the processing corresponding to the preceding block (N-1), processing corresponding to the current block (N) is performed according to the data stored in the other buffer, and at the same time, data held in the next block (N+1) is converted into the execute form and then stored in the one buffer.
Such a conversion of data accommodated in the next block into the execute form during the execution of the process corresponding to the current block will settle the above-noted problems to some extent. In the case of successive executing a plurality of blocks of short execution times, the movable machine part may still sometimes come to a halt between the blocks. That is, when the blocks have short execution times, there are cases where even after completion of the process corresponding to the current block the data in the next block has not yet been converted into the execute form. Also in such a case, the movable machine part will stop between the blocks, similarly presenting the problems that the workpiece will be stained with a cutter mark and subject to vibration.
The present invention offers a solution to the above-mentioned problems and has for its object to prevent the movable machine part from stopping even when a plurality of blocks having short execution times are executed in succession.